The present invention is directed to the removal of fine particles from gases. In particular, the present invention facilitates the separation and collection of particulate matter, such as dust, mist, fumes, smoke, and also of noxious gases etc., dispersed in a gas, in a state of turbulent flow, by taking advantage of certain effects associated with turbulence in a novel and particular way, using purely mechanical means.
It is well known to those skilled in the art of fluid mechanics and related fields of endeavour, that fine particles dispersed in a fluid in a turbulent state of flow tend to follow the eddies of the turbulent fluid.
The removal of very fine particles, typically in the range of about 0.01 to 100 microns, from industrial gases or ambient air, is a difficult and expensive operation to perform efficiently. Devices traditionally employed for this purpose involve electrostatic precipitators, a variety of filters, and wet scrubbers. Scrubbers are used also for the removal of noxious gases from industrial gases. Cyclone collectors have been traditionally used for the removal of particulate matter larger than about 5 microns, and a concerted effort has been made recently to extend their effective range down to about 1 micron particulate size.
In published International Patent Application WO93/15822 and corresponding U.S. application Ser. No. 08/290,883, filed Sep. 13, 1994, the disclosure of which is incorporated herein by reference, there is described a method for the removal of dispersed fine particulates from a fluid stream using the mixing effects of turbulence for the separation and collection of the fine particulates in a novel and specific way, by passing the fluid stream in a state of turbulent flow through a channel not containing any obstructions, alongside of which there is a region, freely communicating with the flow channel, in which the flow is hindered by a large number of objects, placed close to each other in the flow path, causing a change from turbulent to viscous flow. Turbulent eddies, carrying particulates, keep penetrating into this region, which forms an expanded viscous sublayer, and deposit their particulate matter on the surfaces of the objects present there. Retention of the particulates on the surfaces is enhanced if the objects are charged with static electricity. Devices operating on the above principles of particulate collection from fluid streams will be referred to as "turbulent flow precipitators".